Authentication

Programmatic use of CNPJAPI is authenticated with an API key sent in the Authorization header, in Bearer format:

Authorization: Bearer cnpj_sua_chave

The key identifies your account, applies your plan's limits and enables usage-based billing.

How to generate your API key

1. Create your account at https://app.cnpjapi.com.br (there is a free plan to get started).
2. In the portal, generate your API key.
3. Send it in the Authorization header of every request (see Look up a CNPJ).

Treat the API key as a secret: keep it on the server (environment variables or a secrets vault), never in public code, repositories or front-end applications.

Open web lookup vs. programmatic use

The one-off web lookup (the search at https://cnpjapi.com.br) is open and requires no signup - it is meant to check a CNPJ on the spot, from the browser.

The API key is for programmatic use: it identifies your account, applies the plan limits and enables integration into systems, ERPs, CRMs and registration flows.

Authentication errors

See all codes in Errors.